1. Field of the Invention
The present invention relates to an instrument for an endoscope, which is inserted into a body cavity through a channel of the endoscope and injects a drug solution into a tissue region in the body cavity, that is, a needle for an endoscope.
2. Description of the Related Art
As one of the techniques carried out by an endoscope, there is a technique by which an injection needle is inserted into a body cavity through the channel of the endoscope and which injects a drug solution, etc., into a lesion in the body cavity. As a treatment instrument used for the technique, a needle for an endoscope, which has a double-tube structure, has been proposed. The needle for an endoscope is provided with an inner tube to which a hollow needle is connected, and an outer tube for retaining the inner tube, which is inserted in the interior thereof, so as to extend and retract the same, for example, as disclosed in Japanese Published Unexamined Patent Application No. 2001-58006.
The way of using the needle for an endoscope is as follows. First, both tubes are inserted into the channel and are inserted into a body cavity. Next, a needle is extended from the distal end of the outer tube by pushing the inner tube into the outer tube, and is inserted into a bodily tissue in the body cavity, wherein a drug solution supplied in the inner tube is injected.
Also, in a field differing from injection, a derivation biopsy needle has been proposed as a treatment instrument for inserting a needle into a body cavity as disclosed in, for example, U.S. Pat. No. 4,791,937, which suctions bodily tissue by inserting a hollow needle for biopsy.
Japanese Published Patent Application No. 2001-58006 discloses a needle for an endoscope, which endoscopically injects various types of drug solutions into a tissue or blood vessel via an inner tube. With respect to a method for use, a syringe is attached to the ferrule at the proximal end of the inner tube, and a drug solution to be used is filled in the inner tube. Also, a needle for an endoscope is inserted into the channel of the endoscope, and the distal end of the tube is extended from the distal end of the endoscope. After that, the inner tube is extended from the outer tube, and a needle tip secured at the distal end of the inner tube is inserted into a tissue or blood vessel, whereby the drug solution can be injected into the tissue or blood vessel by pushing the syringe.